Legend:

µRoar is a free client library used to access RoarAudio servers. It provides a simple interface to do basic operations like playing back some music. It is much smaller than libroar and under LGPLv3 (libroar is under GPLv3). This allows developers of non-free software to use this library while they are forbidden to use libroar. This is the reason development of it was started: to allow a non-free application to use RoarAudio in one of it's plugins.